Canal configuration of mandibular first premolars in an Egyptian population

The purpose of this study was to investigate canal configuration of mandibular first premolars in an egyptian population. two hundred fifty human extracted mandibular first premolars were collected from egyptian patients and a small hole in the center of the occlusal surface of each tooth was made perforating the roof of the pulp chamber. teeth were decalcified by immersing in nitric acid and dehydrated in ascending concentrations of ethyl alcohol. a waterproof black ink was passively injected from the occlusal hole into pulp system and stained teeth were immersed in methyl salicylate solution for clearing. standardized pictures of the cleared teeth were obtained and anatomical features of the root canal were observed. the average length of the mandibular first premolar teeth was 22.48 ±1.74 mm, one-rooted teeth were 96.8% and the two-rooted were 3.2%. vertucci type i canal configuration represented the highest percentage (61.2%) followed by type v (16.4%), type iv (13.2%), type ii (5.6%) and type iii (2.8%). vertucci type vi canal configuration represented the lowest percentage (0.4%) and a complex configuration was found in one tooth. accessory canals were detected in 22.8% and inter-canal connections were observed in 24.8% while 54% showed apical delta. such knowledge is clinically useful for localization and negotiation of canals of mandibular first premolar, as well as their subsequent management in egyptian population.